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Abstract:

The disclosure relates to a method and apparatus for preventing oxidation
or contamination during a circuit printing operation. The circuit
printing operation can be directed to OLED-type printing. In an exemplary
embodiment, the printing process is conducted at a load-locked printer
housing having one or more of chambers. Each chamber is partitioned from
the other chambers by physical gates or fluidic curtains. A controller
coordinates transportation of a substrate through the system and purges
the system by timely opening appropriate gates. The controller may also
control the printing operation by energizing the print-head at a time
when the substrate is positioned substantially thereunder.

Claims:

1. A system for depositing an organic material on a substrate,
comprising: a housing comprising at least a first chamber and a second
chamber; an opening in at least one side of each of the first and second
chambers; one or more seals for reversibly closing the opening in each of
the first and second chambers; a print head disposed within the second
chamber; a gas-bearing surface comprising a plurality of vacuum and
pressure ports disposed within the second chamber; at least one transport
mechanism for moving the substrate into and out of the second chamber; a
vacuum source adapted for communication with at least one of the
chambers; and, an inert-gas source adapted for communication with at
least one of the chambers.

2. The system of claim 1, wherein said first chamber comprises an inlet
chamber.

3. The system of claim 1, wherein said first chamber comprises both an
inlet and an outlet chamber.

4. The system of claim 1, wherein said second chamber comprises a print
head chamber.

5. The system of claim 1, wherein said housing further comprises a third
chamber.

6. The system of claim 5, wherein said first, second, and third chambers
are disposed in line with one another.

7. The system of claim 5, wherein said third chamber comprises an outlet
chamber.

8. The system of claim 5, wherein said housing further comprises a fourth
chamber.

9. The system of claim 8, wherein a plurality of said chambers provide an
inert-gas environment.

10. The system of claim 8, wherein at least one of said chambers
comprises a load lock chamber.

11. The system of claim 5, wherein said second chamber is disposed
between said first chamber and said third chamber.

12. The system of claim 11, wherein said second chamber is disposed
adjacent at least one of said first and third chambers.

13. The system of claim 1, wherein said second chamber is adapted for
communication with a vacuum source.

14. The system of claim 1, further comprising a gas input in said
housing.

15. The system of claim 14, wherein said second chamber is adapted for
communication with said inert-gas source.

16. The system of claim 15, wherein said inert-gas source comprises a
noble-gas source.

17. The system of claim 15, wherein said inert-gas source comprises a
nitrogen source.

18. The system of claim 1, wherein said opening is defined at least in
part by an open gate or partition.

19. The system of claim 1, wherein at least one of said chambers
comprises opposing sides, with each of said opposing sides comprising an
opening.

20. The system of claim 1, wherein each of at least two of said chambers
comprises opposing sides, with each of said opposing sides comprising an
opening.

21. The system of claim 1, wherein at least one of said seals comprises a
closed gate or partition.

22. The system of claim 1, wherein at least one of said seals comprises
means for sealing a respective one of said chambers from the rest of said
housing.

23. A method for forming a film of a selected material on a substrate,
comprising: receiving a substrate at a substrate-inlet region;
transporting the substrate to a substrate-printing region; providing an
inert-gas environment at the substrate-printing region; floating the
substrate at the substrate-printing region; while floating the substrate,
printing a film of a selected material on the substrate; transporting the
substrate away from the substrate-printing region; and, removing the
substrate from a substrate-outlet region.

24. The method of claim 23, further comprising: isolating the
substrate-inlet region; and, providing the substrate-inlet region with an
inert-gas environment.

25. The method of claim 23, further comprising: isolating the
substrate-printing region.

26. The method of claim 23, wherein said substrate is floated using a
combination of pressure and vacuum.

Description:

[0001] The application claims the filing-date priority of Provisional
Application No. 61/142,575, filed Jan. 5, 2009, the disclosure of which
is incorporated herein in its entirety; the application also claims
priority to U.S. patent application Ser. No. 12/139,391, filed Jun. 13,
2008, the disclosure of which is incorporated herein in its entirety;
this application also claims priority to U.S. patent application Ser. No.
12/652,040, filed Jan. 5, 2010, the disclosure of which is incorporated
herein in its entirety.

BACKGROUND

[0002] 1. Field of the Invention

[0003] The disclosure relates to a method and apparatus for efficient
deposition of a patterned film on a substrate. More specifically, the
disclosure relates to a method and apparatus for supporting and
transporting a substrate on gas bearing during thermal jet printing of
material on a substrate.

[0004] 2. Description of Related Art

[0005] The manufacture of organic light emitting devices (OLEDs) requires
depositing one or more organic films on a substrate and coupling the top
and bottom of the film stack to electrodes. The film thickness is a prime
consideration. The total layer stack thickness is about 100 nm and each
layer is optimally deposited uniformly with an accuracy of better than
.+-0.1 nm. Film purity is also important. Conventional apparatuses form
the film stack using one of two methods: (1) thermal evaporation of
organic material in a relative vacuum environment and subsequent
condensation of the organic vapor on the substrate; or, (2) dissolution
of organic material into a solvent, coating the substrate with the
resulting solution, and subsequent removal of the solvent.

[0006] Another consideration in depositing the organic thin films of an
OLED is placing the films precisely at the desired location on the
substrate. There are two conventional technologies for performing this
task, depending on the method of film deposition. For thermal
evaporation, shadow masking is used to form OLED films of a desired
configuration. Shadow masking techniques require placing a well-defined
mask over a region of the substrate followed by depositing the film over
the entire substrate area. Once deposition is complete, the shadow mask
is removed. The regions exposed through the mask define the pattern of
material deposited on the substrate. This process is inefficient as the
entire substrate must be coated, even though only the regions exposed
through the shadow mask require a film. Furthermore, the shadow mask
becomes increasingly coated with each use, and must eventually be
discarded or cleaned. Finally, the use of shadow masks over large areas
is made difficult by the need to use very thin masks (to achieve small
feature sizes) that make said masks structurally unstable. However, the
vapor deposition technique yields OLED films with high uniformity and
purity and excellent thickness control.

[0007] For solvent deposition, ink jet printing can be used to deposit
patterns of OLED films. Ink jet printing requires dissolving organic
material into a solvent that yields a printable ink. Furthermore, ink jet
printing is conventionally limited to the use of single layer OLED film
stacks, which typically have lower performance as compared to multilayer
stacks. The single-layer limitation arises because printing typically
causes destructive dissolution of any underlying organic layers. Finally,
unless the substrate is first prepared to define the regions into which
the ink is to be deposited, a step that increases the cost and complexity
of the process, ink jet printing is limited to circular deposited areas
with poor thickness uniformity as compared to vapor deposited films. The
material quality is also lower due to structural changes in the material
that occur during the drying process and due to material impurities
present in the ink. However, the ink jet printing technique is capable of
providing patterns of OLED films over very large areas with good material
efficiency.

[0008] No conventional technique combines the large area patterning
capabilities of ink jet printing with the high uniformity, purity, and
thickness control achieved with vapor deposition for organic thin films.
Because ink jet processed single layer OLED devices continue to have
inadequate quality for widespread commercialization, and thermal
evaporation remains impractical for scaling to large areas, it is a major
technological challenge for the OLED industry to develop a technique that
can offer both high film quality and cost-effective large area
scalability.

[0009] Manufacturing OLED displays may also require the patterned
deposition of thin films of metals, inorganic semiconductors, and/or
inorganic insulators. Conventionally, vapor deposition and/or sputtering
have been used to deposit these layers. Patterning is accomplished using
prior substrate preparation (e.g., patterned coating with an insulator),
shadow masking as described above, and when a fresh substrate or
protective layers are employed, conventional photolithography. Each of
these approaches is inefficient as compared to the direct deposition of
the desired pattern, either because it wastes material or requires
additional processing steps. Thus, for these materials as well there is a
need for a method and apparatus for depositing high-quality, cost
effective, large area scalable films.

[0010] Certain applications of thermal jet printing require non-oxidizing
environment to prevent oxidation of the deposited materials or associated
inks. In a conventional method, a sealed nitrogen tent is used to prevent
oxidation. Conventional systems use a floating system to support and move
the substrate. A floatation system can be defined as a bearing system of
alternative gas bearings and vacuum ports. The gas bearings provide the
lubricity and non-contacting support for the substrate, while the vacuum
supports the counter-force necessary to strictly control the height at
which the relatively light-weight substrate floats. Since high-purity
nitrogen gas can be a costly component of the printing system, it is
important to minimize nitrogen loss to the ambient.

[0011] Accordingly, there is a need for load-locked printing system which
supports a substrate on gas bearings while minimizing system leakage and
nitrogen loss.

SUMMARY

[0012] The disclosure relates to a method and apparatus for preventing
oxidation or contamination during a thermal jet printing operation. The
thermal jet printing operation may include OLED printing and the printing
material may include suitable ink composition. In an exemplary
embodiment, the printing process is conducted at a load-locked printer
housing having one or more chambers. Each chamber is partitioned from the
other chambers by physical gates or fluidic curtains. A controller
coordinates transportation of a substrate through the system and purges
the system by timely opening appropriate gates. The substrate may be
transported using gas bearings which are formed using a plurality of
vacuum and gas input portals. The controller may also provide a
non-oxidizing environment within the chamber using a gas similar to, or
different from, the gas used for the gas bearings. The controller may
also control the printing operation by energizing the print-head at a
time when the substrate is positioned substantially thereunder.

[0013] In one embodiment, the disclosure relates to a method for printing
a film of OLED material on a substrate by (i) receiving the substrate at
an inlet chamber; (ii) flooding the inlet load-locked chamber with a
noble gas and sealing the inlet chamber; (iii) directing at least a
portion of the substrate to a print-head chamber and discharging a
quantity of OLED material from a thermal jet discharge nozzle onto the
portion of the substrate; (iv) directing the substrate to an outlet
chamber; (v) partitioning the print-head chamber from the outlet chamber;
and (vi) unloading the print-head from the outlet chamber. In one
embodiment of the invention, the print-head chamber pulsatingly delivers
a quantity of material from a thermal jet discharge nozzle to the
substrate.

[0014] In another embodiment, the disclosure relates to a method for
depositing a material on a substrate. The method includes the steps of:
(i) receiving the substrate at an inlet chamber; (ii) flooding the inlet
chamber with a chamber gas and sealing the inlet chamber; (iii) directing
at least a portion of the substrate to a print-head chamber and
discharging a quantity of material from a thermal jet discharge nozzle
onto the portion of the substrate; (iv) directing the substrate to an
outlet chamber; (v) partitioning the print-head chamber from the outlet
chamber; and (vi) unloading the print-head from the outlet chamber. The
print-head chamber pulsatingly delivers a quantity of material from a
thermal jet discharge nozzle to the substrate.

[0015] In another embodiment, the disclosure relates to a load-locked
printing apparatus, comprising an inlet chamber for receiving a
substrate, the inlet chamber having a first partition and a second
partition; a print-head chamber in communication with the inlet chamber,
the print-head chamber having a discharge nozzle for pulsatingly metering
a quantity of ink onto a substrate, the second partition separating the
print-head chamber from the inlet chamber; an outlet chamber in
communication with the print-head chamber through a third partition, the
outlet chamber receiving the substrate from print head chamber and
exiting the substrate from a fourth chamber. In a preferred embodiment,
the inlet chamber, the print-head chamber and the outlet chamber provide
an inert gas environment while the discharge nozzle pulsatingly meters
the quantity of ink onto the substrate. Although the implementation of
the invention are not limited thereto, the inert gas environment can be a
noble gas (e.g. argon, helium, nitrogen or hydrogen).

[0016] In still another embodiment, the disclosure relates to a
load-locked thermal jet printing system. The system includes a housing
with an inlet partition and an outlet partition. The housing defines a
print-head chamber for depositing a quantity of ink onto a substrate. The
housing also includes an inlet partition and an outlet partition for
receiving and dispatching the substrate. A gas input provides a first gas
to the housing. A controller communicates with the print-head chamber,
the gas input and the inlet and outlet partitions. The controller
comprises a processor circuit in communication with a memory circuit, the
memory circuit instructing the processor circuit to (i) receive the
substrate at the inlet partition; (ii) purge the housing with the first
gas; (iii) direct the substrate to a discharge nozzle at the print-head
chamber; (iv) energize the thermal jet discharge nozzle to pulsatingly
deliver a quantity of film material from the discharge nozzle onto the
substrate; and (v) dispatch the substrate from the housing through the
outlet partition.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] These and other embodiments of the disclosure will be discussed
with reference to the following exemplary and non-limiting illustrations,
in which like elements are numbered similarly, and where:

[0018] FIG. 1 is a schematic representation of a conventional substrate
floatation system;

[0019] FIG. 2 is a schematic representation of an exemplary load-locked
printing housing;

[0020] FIG. 3 is a schematic representation of the load-locked printing
housing of FIG. 2 receiving a substrate;

[0021] FIG. 4 schematically shows the substrate received at the print-head
chamber of the housing;

[0022] FIG. 5 schematically shows the completion of the printing process
of FIGS. 3 and 4;

[0023] FIG. 6 is a schematic representation of a print-head for use with
the load-locked housing of FIG. 2; and

[0024] FIG. 7 is an exemplary load-locked system according to an
embodiment of the invention;

[0025] FIG. 8 shows several types of substrate misalignment within the
print system, and

[0026] FIG. 9 shows a substrate pattern including fiducials and initial
locus of area viewed by a camera or other imaging devices.

DETAILED DESCRIPTION

[0027] FIG. 1 is a schematic representation of a conventional substrate
floatation system. More specifically, FIG. 1 shows a portion of a
flotation system in which substrate 100 is supported by air bearings. The
air bearings are shown schematically as arrows entering and leaving
between baffles 110. The substrate floatation system of FIG. 1 is
typically housed in a sealed chamber (not shown). The chamber includes
multiple vacuum outlet ports and gas bearing inlet ports, which are
typically arranged on a flat surface. Substrate 100 is lifted and kept
off a hard surface by the pressure of a gas such as nitrogen. The flow
out of the bearing volume is accomplished by means of multiple vacuum
outlet ports. The floating height is typically a function of the gas
pressure and flow. In principle, any gas can be utilized for such a
substrate floatation system; however, in practice it is preferable to
utilize a floatation gas that is inert to the materials that come into
contact with the gas. As a result, it is conventional to use noble gases
(e.g., nitrogen, argon, and helium) as they usually demonstrate
sufficient inertness.

[0028] The floatation gas is an expensive component of the substrate
floatation system. The cost is compounded when the printing system calls
for substantially pure gas. Thus, it is desirable to minimize any gas
loss to the environment.

[0029] FIG. 2 is a simplified representation of an exemplary load-locked
printing housing according to one embodiment of the disclosure. Housing
200 is divided into three chambers, including inlet chamber 210,
print-head chamber 220 and outlet chamber 230. As will be discussed, each
chamber is separated from the rest of housing 200 through a gate or a
partition. In one embodiment of the disclosure the gates or partitions
substantially seal the chambers from the ambient environment and from the
rest of housing 200. In another embodiment of the disclosure (not shown),
chamber 230 is not included in housing 200, and chamber 210 is utilized
as both an inlet and an outlet chamber.

[0030] FIG. 3 is a schematic representation of the load-locked printing
housing of FIG. 2 receiving a substrate. During operation, substrate 350
is received at inlet chamber 310 through inlet gates 312. Inlet gates 312
can comprise a variety of options, including single or multiple moving
gates. The gates can also be complemented with an air curtain (not shown)
for minimizing influx of ambient gases into inlet chamber 310.
Alternatively, the gates can be replaced with air curtains acting as a
partition. Similar schemes can be deployed in all gates of the housing.
Once substrate 350 is received at inlet chamber 310, inlet gates 312
close. The substrate can then be detained at inlet chamber 310. At this
time, the inlet chamber can be optionally purged from any ambient gases
and refilled with the desired chamber gas, which is conventionally
selected to be the same as the floatation gas, e.g. pure nitrogen or
other noble gases. During the purging process, print-head inlet gate 322
as well as inlet gate 312 remain closed. Print-head inlet gate 322 can
define a physical or a gas curtain. Alternatively, print-head inlet gate
322 can define a physical gate similar to inlet gate 312.

[0031] FIG. 4 schematically shows the substrate received at the print-head
chamber of the housing. Air bearings can be used to transport substrate
450 from inlet chamber 410 through print-head inlet gate 422 and into
print-chamber 420. Print-head chamber 420 houses the thermal jet
print-head, and optionally, the ink reservoir. The printing process
occurs at print-head chamber 420. In one implementation of the invention,
once substrate 450 is received at print-head chamber 420, print-head
gates 422 and 424 are closed during the printing process. Print-head
chamber can be optionally purged with a chamber gas (e.g., high purity
nitrogen) for further purification of the printing environment. In
another implementation, substrate 450 is printed while gates 422 and 424
remain open. During the printing operation, substrate 450 can be
supported by air bearings. The substrate's location in relation to
housing 400 can be controlled using a combination of air pressure and
vacuum, such as those shown in FIG. 1. In an alternative embodiment, the
substrate is transported through housing 400 using a conveyer belt.

[0032] Once the printing process is complete, the substrate is transported
to the outlet chamber as shown in FIG. 5. Here, print-head gates 522 and
524 are closed to seal off outlet chamber 530 from the remainder of
housing 500. Outlet gate 532 is opened to eject substrate 550 as
indicated by the arrow. The process shown in FIGS. 3-5 can be repeated to
continuously print OLED materials on multiple substrates. Alternatively,
gates 512, 522, 524 and 532 can be replaced with air curtains to provide
for continuous and uninterrupted printing process. In another embodiment
of the disclosure, once the printing process is complete, the substrate
is transported back to the inlet chamber 310 through gate 322, where gate
322 can be subsequently sealed off and gate 312 opened to eject the
substrate. In this embodiment, inlet chamber 310 functions also as the
outlet chamber, functionally replacing outlet chamber 530.

[0033] The print-head chamber houses the print-head. In a preferred
embodiment, the print-head comprises an ink chamber in fluid
communication with nozzle. The ink chamber receives ink, comprising
particles of the material to be deposited on the substrate dissolved or
suspended in a carrier liquid, in substantially liquid form from a
reservoir. The ink head chamber then meters a specified quantity of ink
onto an upper face of a thermal jet discharge nozzle having a plurality
of conduits such that upon delivery to the upper face, the ink flows into
the conduits. The thermal jet discharge nozzle is activated such that the
carrier liquid is removed leaving behind in the conduits the particles in
substantially solid form. The thermal jet discharge nozzle is then
further pulsatingly activated to deliver the quantity of material in
substantially vapor form onto the substrate, where it condenses into
substantially solid form.

[0034] FIG. 6 is a schematic representation of a thermal jet print-head
for use with the load-locked housing of FIG. 2. Print-head 600 includes
ink chamber 615 which is surrounded by top structure 610 and energizing
element 620. Ink chamber 615 is in liquid communication with an ink
reservoir (not shown). Energizing element 620 can comprise a
piezoelectric element or a heater. Energizing element 620 is energized
intermittently to dispense a metered quantity of ink, optionally in the
form of a liquid droplet, on the top surface of the thermal jet discharge
nozzle 640.

[0035] Bottom structure 630 supports nozzle 640 through brackets 660.
Brackets 660 can include and integrated heating element. The heating
element is capable of instantaneously heating thermal jet discharge
nozzle 640 such that the ink carrier liquid evaporates from the conduits
650. The heating element is further capable of instantaneously heating
the thermal jet discharge nozzle 650 such that substantially solid
particles in the discharge nozzle are delivered from the conduits in
substantially vapor form onto the substrate ,where they condense into
substantially solid form.

[0036] Print-head 600 operates entirely within the print-head chamber 220
and housing 200 of FIG. 2. Thus, for properly selected chamber and
floatation gases (e.g. high purity nitrogen in most instances), the ink
is not subject to oxidation during the deposition process. In addition,
the load-locked housing can be configured to receive a transport gas,
such as a noble gas, for carrying the material from the thermal jet
discharge nozzle 640 onto the substrate surface. The transport gas may
also transport the material from the thermal jet discharge nozzle 640 to
the substrate by flowing through conduits 650. In a preferred embodiment,
multiple print-heads 600 are arranged within a load-locked print system
as an array. The array can be configured to deposit material on a
substrate by activating the print-heads simultaneously or sequentially.

[0037] FIG. 7 is an exemplary load-locked system according to an
embodiment of the invention. Load-locked system of FIG. 7 includes a
housing with inlet chamber 710, print-head chamber 720 and outlet chamber
730. Inlet chamber 710 communicates through gates 712 and 722. Print-head
chamber 720 receives substrate 750 from the inlet chamber and deposits
organic LED material thereon as described in relation to FIG. 6. Gate 724
communicates substrate 750 to outlet chamber 730 after the printing
process is completed. The substrate exists outlet chamber 730 through
gate 732.

[0038] Vacuum and pressure can be used to transport substrate 750 through
the load-locked system of FIG. 7. To control transporting the substrate,
controller 770 communicates with nitrogen source 762 and vacuum 760
through valves 772 and 774, respectively. Controller 770 comprises one or
more processor circuits (not shown) in communication with one or more
memory circuit (not shown). The controller also communicates with the
load-locked housing and ultimately with the print nozzle. In this manner,
controller 770 can coordinate opening and closing gates 712, 722, 724 and
732. Controller 770 can also control ink dispensing by activating the
piezoelectric element and/or the heater (see FIG. 6). The substrate can
be transported through the load-locked print system through air bearings
or by a physical conveyer under the control of the controller.

[0039] In an exemplary operation, a memory circuit (not shown) of
controller 770 provides instructions to a processor circuit (not shown)
to: (i) receive the substrate at the inlet partition; (ii) purge the
housing with the first gas; (iii) direct the substrate to a discharge
nozzle at the print-head chamber; (iv) energize the discharge nozzle to
pulsatingly deliver a quantity of material from the thermal jet discharge
nozzle onto the substrate; and (v) dispatch the substrate from the
housing through the outlet partition. The first gas and the second gas
can be different or identical gases. The first and/or the second gas can
be selected from the group comprising nitrogen, argon, and helium.

[0040] Controller 770 may also identify the location of the substrate
through the load-locked print system and dispense ink from the print-head
only when the substrate is at a precise location relative to the
print-head.

[0041] Another aspect of the invention relates to registering the
substrate relative to the print-head. Printing registration is defined as
the alignment and the size of one printing process with respect to the
previous printing processes performed on the same substrate. In order to
achieve appropriate registration, the print-head and the substrate need
to be aligned substantially identically in each printing step. In one
implementation of the invention, the substrate is provided with
horizontal motion (i.e., motion in the x direction) and the print-head is
provided with another horizontal motion (i.e., motion in the y
direction). The x and y directions may be orthogonal to each other. With
this arrangement, the movement of the print-head with respect to the
substrate can be defined with a combination of these two horizontal
directions.

[0042] When the substrate is loaded onto a load-locked system, the areas
to be printed are usually not perfectly aligned in the x and y directions
of the system. Thus, there is a need for detecting the misalignment,
determining the required corrections to the motion of the print-head
relative to the substrate and applying the corrections.

[0043] According to one embodiment of the invention, the pattern or the
previous printing is detected using a pattern recognition system. This
pattern can be inherent in the previous printing or may have been added
deliberately (i.e., fiducials) for the pattern recognition step. By means
of its recognition of the pattern, the misalignment of the substrate to
the printing system's motion, direction or axis can be determined. This
manifests itself as a magnification misalignment, a translational
misalignment and an angular misalignment.

[0044] FIG. 8 shows several types of substrate misalignment within the
print system, including translational misalignment, rotational
misalignment, magnification misalignment and combinational misalignment.
For each print-head scan motion relative to the substrate, the pattern
recognition system will look for and find/recognize the desired pattern.
The pattern recognition system can optionally be integrated with the
controller (see FIG. 7). The pattern recognition system will look for and
find/recognize the desired pattern. The pattern recognition system will
provide the degree of error/misalignment in the x and y directions to the
system's controller, which will then reposition the print-head and
substrate to eliminate the error/misalignment. This means that for
several motions of the print-head with respect to the substrate, the
motion control system will check for misalignment and make the necessary
corrections.

[0045] Alternatively, an initial scan of the entire substrate can be
performed by the pattern recognition system utilizing the x and y motions
available in the printing system. FIG. 9 shows a substrate pattern
including fiducials and initial locus of area viewed by a camera or other
imaging devices. In FIG. 9, fiducials or alignment targets are identified
as boxes 910 in each replicated "pixel." Each pixel in this example, and
in many OLED applications, comprises three sub-pixels each having a
distinct color: red, green, and blue (RGB). The camera or the pattern
recognition device initially focuses on an area of the substrate
identified by circle 930. Once the amount of misalignment is determined,
the motion control system can compensate for the misalignment by causing
the x and the y directions to move in a rotated and translated set of
axes xl and yl such that these axis are a linear combination of
the previous motions.

[0046] For either alignment technique, the printing control system will
then cause the print-head to fire appropriately at the desired print axis
as it scans the substrate. In the case of the embodiment described above,
the print system will periodically use the pattern recognition system to
update and adjust for any misalignment, causing the print-head to fire
after alignment has been achieved. Depending on the degree of
misalignment, the required update and adjustment steps may have to be
repeated more often during the printing operations. Alternatively, the
pattern recognition system must scan the substrate initially to assess
the amount and direction of misalignment, then printing control system
will utilize the misalignment information to adjust the print-head firing
accordingly.

[0047] While the principles of the disclosure have been illustrated in
relation to the exemplary embodiments shown herein, the principles of the
disclosure are not limited thereto and include any modification,
variation or permutation thereof. For example, while the exemplary
embodiments are discussed in relation to a thermal jet discharge nozzle,
the disclosed principles can be implemented with different type of
nozzles. Moreover, the same or different gases can be used for floating
the substrate and for providing a non-oxidizing environment within the
chamber. These gases need not be noble gases. Finally, the substrate may
enter the system from any direction and the schematic of a tri-chamber
system is entirely exemplary.